Lipase-catalyzed synthesis of 1,3-diacylglycerols containing stearidonic, γ-linolenic and α-linolenic acids in a solvent-free system

Abstract

1,3-Diacylglycerols (1,3-DAG) are minor components in edible oils with potential for the management of overweight and obesity. In this work, 1,3-DAG containing stearidonic acid (SDA), γ-linolenic acid (GLA), and α-linolenic acid (ALA), were synthesized by lipase-mediated catalysis following a Taguchi experimental design. SDA, GLA, and ALA are polyunsaturated fatty acids (PUFA) able to act as precursors of anti-inflammatory lipid mediators in the human body and may help with prevention or relief of inflammatory diseases. Solvent-free synthesis of 1,3-DAG was successfully performed by esterifying glycerol with free fatty acids (FFA) obtained from Echium plantagineum seed oil. Crude reaction products were further purified by saponification. Two lipases (Lipozyme® RM-IM and Lipozyme® 435) and three variables (substrate molar ratio, lipase load and reaction time) were used to optimize the reaction conditions. At the optimal conditions, 88.7 mol% of DAG was produced (68.0 mol% 1,3-DAG and 20.7 mol% 1,2-DAG) using Lipozyme® 435 at 60 °C, a glycerol:FFA molar ratio of 1:3, a lipase load of 2.0 wt%, and 4 h reaction time. Proportions of SDA, GLA and ALA in the 1,3-DAG were 32.7, 32.3 and 22.0% respectively. The synthesized 1,3-DAG have potential as functional ingredients in foods for weight and obesity management.